The present application is a Continuation-In-Part Application of a U.S. patent application Ser. No. 028,760 entitled "INDUSTRIAL PLAYBACK ROBOT" filed Mar. 23, 1987, abandoned.
The present invention generally relates to industrial playback robots designed to play back operations based on teaching data which are entered into the robot beforehand, and more particularly to an industrial playback robot which can be taught with ease.
When teaching an industrial playback robot, the teaching operation may be carried out either according to the point to point (hereinafter simply referred to as PTP) control (or sequential positioning control) which teaches discrete operating points to the robot or according to the continuous path (hereinafter simply referred to as CP) control which continuously teaches operating points to the robot. However, according to the CP control, position data related to the operating points are continuously stored into a memory means and this memory means must thus have a large memory capacity. On the other hand, according to the PTP control, only position data related to predetermined operating points need to be stored into the memory means, and for this reason, the required memory capacity of the memory means is greatly reduced compared to the case where the CP control is employed.
But according to the PTP control, it is impossible to teach the robot by use of a teaching handle which is connected to an articulated arm of the robot in a case where the robot is to carry out operations within a small space such as inside a vehicle. In this case, a first operator manually moves a movable part (for example, an arm) of the robot, and a second operator manipulates a teaching switch to store a teaching datum such as a position datum of an operating point into the memory means when the movable part reaches a teaching position.
In other words, in the conventional industrial playback robot employing the PTP control, at least two operators are required to carry out the teaching. In a teaching mode, the movable part of the robot is freely movable, and it is essential that the first operator supports and moves the movable part while the second operator enters the teaching datum by manipulating the teaching switch. As a result, the conventional industrial playback robot employing the PTP control suffers a disadvantage in that the teaching efficiency is poor.
It is possible to conceive a teaching handle provided with switches for entering predetermined teaching data. However, there are various kinds of teaching data such as data indicating positions where the operation of the robot is to start and end. If the number of switches provided on the teaching handle were to be increased depending on the number of kinds of teaching data, there is a disadvantage in that the construction and wiring of the teaching handle become extremely complex. Furthermore, the number of kinds of teaching data which can be entered becomes limited by the number of switches which can be provided on the teaching handle.
In addition, depending on the shape of the robot and the location of the robot, there are cases where it is impossible to use the teaching handle, as described before. In such cases, the conventional industrial playback robot employing the PTP control can only enter the teaching datum by the two operators.
On the other hand, as methods of teaching the robot, there is the direct teaching method in which the robot is taught manually by the operator and the indirect teaching in which the robot is taught by remote control. In the case of the indirect teaching, keys on an instruction panel must be manipulated in order to instruct which movable part of the robot is to move and in which direction the designated movable part of the robot is to move. Such an instruction is made for each movable part of the robot so that the robot moves to a predetermined operating point or takes a predetermined position.
For example, an articulated robot comprises one shaft about which an arm moves to the right and left, two shafts about which the arm moves back and forth, three shafts about which the arm moves up and down, four shafts about which a wrist moves up and down, five shafts about which the wrist moves to the right and left, and six shafts about which the wrist rotates to the right and left. The part of the robot to be moved may be designated by designating the shaft, and the moving direction in which the designated part is to move or rotate may be designated by designating the rotating direction about the designated shaft. In this case, the designation of the shaft and the designation of the moving direction are made by manipulating appropriate ones of twelve keys which are provided on the instruction panel for each shaft and each moving direction, or by manipulating rotary switches.
In other words, in order to carry out the indirect teaching with respect to the conventional industrial robot, the operator must manipulate appropriate ones of a plurality of keys provided on the instruction panel. For this reason, the selection of the appropriate keys becomes troublesome and difficult for the operator as the number of control elements (that is, shafts and moving directions) of the articulated robot increases, and there is a problem in that the operation efficiency of the teaching operation is poor.
In addition, the teaching data for the robot change depending on the kind of work piece, and the number of kinds of work pieces is usually in the order of several tens. Hence, when carrying out the playback operation, the operator must select appropriate teaching data for the kind of work piece. Conventionally, the operator visually discriminates the kind of work piece and selects the appropriate teaching data by manipulating a switch on an operation panel located within a hazardous location, for example.
Accordingly, the operator must walk to the operation panel to manipulate an appropriate switch when selecting the appropriate teaching data, and the operator must discontinue whatever he is doing when making the selection. Hence, there is a problem in that the operation efficiency of the playback operation is poor.
On the other hand, in the case where the robot is a painting robot and the operation panel must have an explosion-proof construction, an explosion-proof box or a safety circuit such as a barrier is required. Therefore, it is difficult to increase the number of switches on the operation panel without increasing the cost considerably, and it is thus difficult to increase the number of kinds of teaching data for the selection by the operator.